This blog provides updated forecasts and comments on current weather or other topics

Tuesday, January 11, 2011

6 PM Nowcast

The snow is slowly moving in, but nothing much going on in the central Puget Sound yet--the commute for virtually all of you is safe.

Snow has slowly extended from the coast to Shelton and some scattered light snow showers have been reported in the south Sound. Snow has been falling for hours on the north coast across the NW Olympic Peninsula, with light snow across portions of the San Juans into Bellingham now.

Here is the radar image at 5:47 PM from RainWatch. Remember the beam is way above the surface in most places and lot of this snow is not reaching the surface, particularly on the east side of the Sound.. There is one modest band moving through the south Sound, but the stuff behind it is unremarkable. And the easterly flow off the Cascades is really attenuating the snow east of the Sound.

And the snow is running out of time as the temperatures aloft are now warming as warm Pacific air moves in. In 4-6 hours it will be too late!

We don't have a regular radar on the coast, but we do have a vertically pointing radar at Westport (part of NOAA's atmospheric river observatory). Here is the latest image. You can see the lowering cloud deck and precipitation reaching the surface....looks like more intense precipitation moving in there...which would reach Puget Sound in a few hours.

So we have an interesting tug of war over Seattle and the east side--- who will win?...the drying easterlies or the snow band coming in? The models suggest the former!

I'm in Aberdeen, and it looks almost blizzard-esque at 6:35. The stiff easterlies are affixing plenty of snow on east facing road signs and cars, with between and inch and inch and a half accumulating...all this comes at a price, however; I know that we will probably be the first to see it switch to rain.

We're up to 1 1/2" with snow steadily coming down now at 7:05--on a ridge about South Shore of Hood Canal at 550' elevation. Just a hair over 30 degrees on the thermometer and it feels like its going to snow for awhile.

We're up to almost 2" at 7:20 and its coming down steadily. Just over 30 degrees here at 550' elevation just above the South Shore of Hood Canal near Union. It feels like its going to be coming down for awhile.

I'd like to continue the philosophical discussion raised yesterday about the value of extended forecasts. I'm still of two minds. This forecast really went sideways, even within the last 12-24 hours. I realize everyone is trying to do their best and the motivation is strong to be a good citizen and to avoid the problem we had 6 weeks ago that resulted in 12 hour commutes for some. Still, do I want my tax dollars that support the NWS going to perfecting forecasts or telling the entire community to be home by 4PM? Please tell me the odds, tell me when you think the snow will begin, but don't tell me how to run my commute! Maybe the NWS has special liaison with state DOT and other officials, though I doubt it. Maybe the mission of the NWS has changed from forecasting to the life-impacts of the forecasts. But, I'd first like the original purpose to be perfected. I view this blog differently because it is private and educational in purpose. I see Mr. Mass as a citizen trying his best to look out for his fellow citizen. I respect that the blog is personal and also deals with important educational issues like teaching mathematics to our children. He is my neighbor advising me to be in by 4 if I want to safely miss a possible spate of weather, not the government. Still, all of these forecasts have tremendous influence and impact, and folks listen to them with a great deal of deference--too much in today's case. Here in West Seattle it is 7:00 PM and I did not need 4-6 days notice about weather that never happened. So back to the issue of how best to express uncertainties in extended forecasts. I assume these models take into consideration the east winds and the warming aloft, and all other series of contingencies, but it would be nice to deconstruct them and break down for us all the variables that could cause a forecast of snow to be enhanced, or to be diminished, as has been the case thus far today.

Very light snow here in Hansville, but it is snowing fairly hard in Poulsbo. I installed a weather station and webcam at Poulsbo Central Market. It's a pretty good view of the snow right now. http://www.centralmarketweather.com/Poulsbo/webcam/

I just left Northgate and drove to Queen Anne - light to moderate snow and big flakes at NSCC, sticking to the ground. The pavement was clear but wet on I-5 (couldn't decide on the lesser of evils - the salted highway but fast traffic or calmer but snowy side streets/99).In Lower Queen Anne (East side) it's also steady and medium to large flakes with small accumulation on the streets. I have about .25" on my deck rail.

I should have looked more closely at my weather station. Winds are out of the SE mostly and the relative humidity is very low at 53% (DP = 15°). Temperature is now 29.7° at 20:45. Same location as before of course. Wind is blowing harder and still snowing.

Snowing hard here in East Bellevue, 210' elevation, uphill from Lake Sammamish. About an inch on the ground, medium-size flakes, fairly wet. Temp is 31, breeze is 5 mph from the SE with a few gusts (highest today was 17). It's fun to read what everyone else is getting, and the NowCasts are brilliant! Will there be another one tonight, Cliff?

I'm showing 31 degrees in the S. Waterfront area of Pdx with light freezing rain. Traffic seems to be moving just fine through the city though it looks like travelers w. bound on I-84 near cascade locks will be disappointed, jack knifed semi has shut it down. Thanks for the awesome forum for weather Cliff!

Snow on the north end of the Sammamish plateau is extremely 'sparkly'--lots of specular highlights arising from flat crystal faces reflecting the porch light. The effect makes the snow appear very different than what we had a few weeks ago. Wind starting to come up as well.

Beacon Ave S + Cloverdale is home to a stranded Metro bus, a few stray cars and almost an inch of snow. Still coming down though it doesn't //feel// that cold...does that mean it's warming up? Roads are super slick because the snow is sooo darn wet.

Sammamish, 550 ft elevation. We have snow coming down hard with fairly strong winds...10mph, gusting to 25mph from ENE if you can believe the neighborhood weather equipment on Wunderground. The snow is blowing sideways about half the time and sometimes almost UPWARD, because the wind is blowing so hard. It's really difficult to believe that this will turn to rain by 1:00am, but if you say so... ;-).

NWS just issued an updated Winter Storm Warning through 7:00am tomorrow for us in the Hood Canal area. They are calling for 4 to 8 inches. We have about an inch of very fine snow right now and the temperature is dropping.

Calm winds, 1/2" to 3/4" on the ground on the East side of Lake Union in Seattle. First tiny flakes fell at 7:10, Now steady moderate snow and calm winds. Drove at 9:00 to the U district, main roads okay, steep side roads pretty greasy. Temp 33.7 F

Kids are having a grand time outdoors at 10:30pm- we've got nearly 3" on the ground near downtown Burien, with some mixed snow/frozen rain falling. 32.9°F on the thermometer and my kids are hoping the forecasters are all wrong about it warming up and turning to rain.

Checking in again. The snow just stopped here in Bothell. 33F and still dropping...for now. Wish the kids weren't in bed. This is PERFECT snowman weather :( Just measured and found over 2 1/2 inches. And as I am posting, it started dumping snow again. :)

About 2 inches on the ground here in Bellingham... I am near Whatcom Community College. Still snowing and gusty... 15mph. Not even close the being a blizzard but I'm sure some people would use that to describe the conditions right now.

11:30PM in Olympia. (Not that Cliff is still up vetting the posts!)32.2F at the ground, snowing steadily since around 6:30PM, with a good 3" on the ground and no sign of melting.No wind.Still snowing . . . The midnight snowboarders are congregating on the San Francisco St hill where I live.Rescued one stuck car so far ;-)

10 cm now at 1 am in Vancouver BC. Maybe it will reach the 25 cm mark (max predicted) by tomorrow morning when I have to drive my kid to bowling at 7 am. I have all weather tires and they do plow streets in Vancouver.

Can I infer anything about the weather conditions aloft or how a storm is progressing based on the type of snow falling? In Bellingham, early on, the snow was fluffy but very small with nondescript patterns. Later on, the flakes became bigger and had the more traditional snowflake pattern. Then a bit later, the falling flakes were clumped together...then